Tractor having dual hydrostatic drive with single hand control and attachment adapter for powered attachments

ABSTRACT

A tractor has a base for supporting a motive power source, left and right driven wheels, and left and right transmissions for the respective left and right wheels; a handle structure coupled to the base for grasping by an operator from behind the tractor; a drive system for driving each of the left and right transmissions with motive power from the motive power source; wherein the left and right transmissions are hydrostatic transmissions, further having a speed regulator control lever on each transmission that allows seamless control of the transmission from reverse speed through neutral into forward speed; and a transmission control coupled to each speed regulator control lever; further wherein there is a longitudinally disposed space between the left and right transmissions, and a power take off shaft is disposed in the space extending anteriorly and driven by the motive power source for powering a powered attachment arranged to be attached at the anterior of the tractor, further including a shaft extension of said power take off shaft extending posteriorly for driving a rear power take off for powering a rear mounted powered attachment.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of commonly-assigned U.S. application Ser. No.14/616,908, filed Feb. 9, 2015, which is a divisional of U.S.application Ser. No. 13/345,366, filed Jan. 6, 2012, now U.S. Pat. No.8,978,796, issued Mar. 17, 2015 entitled TRACTOR HAVING DUAL HYDROSTATICDRIVE WITH SINGLE HAND CONTROL AND ATTACHMENT ADAPTER FOR POWEREDATTACHMENTS the entire disclosures of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION Field of the Invention

This invention pertains to tractors generally, and in particular, towalk-behind hand tractors also known as mono-axle or two wheel tractors.

Description of the Background

Walk-behind hand tractors, including hand tractors with multipleattachments for performing various grounds maintenance chores have beencommercially available in the marketplace for a long time. An example ofthis can be found in E. L. Rose (U.S. Pat. No. 2,538,708). At present,hand tractors of this type employ a single transmission, either gear orhydrostatically driven, coupled through a differential to the drivewheels. In this current design, the operator makes directional changesto the tractor by applying body weight force to the handles. Stillothers have steering brakes that effectively brake the inside wheelcausing the tractor to turn toward the braked wheel. Unfortunately, theeffect of the differential drive is to transfer all the motion to theunbraked wheel thereby doubling its wheel speed and making the tractordifficult to control. The differential drive also makes the tractorunstable and hard to control on sloped terrain. As the tractor navigatesacross the slope, the operator must use body weight force to counter thetractor's tendency to turn downhill. This can lead to operator fatigueand a loss of traction and control of the hand tractor. A furtherdisadvantage of this design is that motive power is biased to the wheelwith the least grip. This is a particular disadvantage when the tractoris attempting to perform chores where maximum traction is necessary likemowing slopes or moving snow. A still further disadvantage is that thebrake components are subject to premature wear and constant maintenanceand service.

Still other tractors in the prior art utilize wheel drive with ahydrostatic pump-to-motor transmission. This configuration affords theoperator the ability, through valving, to effectively slow down or stopthe inside wheel to cause a turn. These hand tractors, while asubstantial improvement to the differential design, have certaindrawbacks as well. This design does not enable the operator of thetractor to make the wheels rotate in opposing directions to cause a zeroradius turn. Furthermore, these hand tractors have proven to becomplicated and expensive to build and have yielded only limited successin the marketplace.

Still other embodiments exist in the prior art such as Wenzel (U.S. Pat.No. 5,127,215) and Walker (U.S. Pat. No. 7,146,787). These machineseffectively deploy independent dual drive motion control to the drivewheels enabling the operator to perform a zero radius turn. Thesemachines have vertical crankshaft motors that utilize a beltconfiguration in the horizontal plane that connects directly to the lawnmower, or in the case of Walker, to a series of complicated andexpensive gearboxes and drive shafts to power the mowing unit. Thesemachines, while functional for lawn mowing, serve little purpose, ifany, in utilizing other chore performing attachments.

To be complete, it must be mentioned that nowhere in the prior art doesthere exist, to applicant's knowledge, a hand tractor that utilizes anattachment adapting method with integral power take off (PTO), that canbe deployed quickly, easily and safely, by one person without disablingthe hand tractor.

The need exists in the marketplace for a reliable, simply designed,walk-behind hand tractor with independent control to each drive wheelthat has the ability to be operated with one hand and that can rapidlyand safely deploy attachments by a single operator without tools. Todate, to applicant's knowledge, no such hand tractor has been availablein the industry.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a hand tractor that avoidsthe drawbacks associated with the prior art.

More specifically, it is an object of the current invention to provide ahand tractor with dual seamless drive that independently drives left andright wheels from reverse through neutral to maximum forward speed thusproviding clutchless, dynamic control of both speed and direction to thehand tractor.

A further object of the present invention is to provide a tractor thatcan be controlled via a single control with one hand that controlssimultaneously both left and right seamless drive units from reversethrough neutral to a maximum forward speed.

A further object of the current invention is to provide a hand tractorwith controls at the handles that enable the operator to control thehand tractor with independent hand controls or by deployment of a singlelever omni-directional hand control that can simultaneously deploy bothleft and right seamless drive units from reverse through neutral to amaximum forward speed, effectively allowing the user to choose betweentwo-handed operation or single-handed operation as desired.

An even further object of the current invention is to provide a handtractor that provides a means for the operator to select and set adetermined forward speed via a cruise control, e.g., friction device,enabled on the single lever hand control while still maintaining theoperator's ability to control the speed and direction of the handtractor with the independent hand controls.

It is an additional object of this invention to provide a feature forthe independent hand controls and the single hand control to be urgedtoward neutral when the operator releases the hands or hand.

It is still another object of the current invention to provide a meansof rapidly and safely installing and removing chore performing PTOdriven front attachments without the use of tools by a single operatorthrough a self aligning hitch with means for a positive force latchingmechanism with integral PTO drive shaft alignment, coupling andengagement.

It is an additional object of the current invention to utilize a rapidlydeployable front mounted attachment adapter and integral PTO that usesthe biased weight of the tractor to pull the attachment into thelatching mechanism so that a single operator can install attachmentsunaided.

It is still a further object of this invention to provide a means forattaching a rear PTO and attachment adapter that can be deployedsimultaneously with the front PTO attachment adapter.

In accordance with an embodiment of the invention, a tractor is providedcomprising a base for supporting a motive power source, left and rightdriven wheels, and left and right transmissions for the respective leftand right wheels; a handle structure coupled to the base for grasping byan operator from behind the tractor; a drive system for driving each ofthe left and right transmissions with motive power from the motive powersource; further comprising a single lever hand control for operation bya single hand of the operator for controlling both left and righttransmissions seamlessly each between reverse speed through neutral andforward speed.

In accordance with another embodiment, a tractor is provided comprisinga base for supporting a motive power source, left and right drivenwheels and left and right hydrostatic transmissions for the respectiveleft and right wheels; a handle structure coupled to the base forgrasping by an operator from behind the tractor; a drive system fordriving each of the left and right transmissions with motive power fromthe motive power source, further wherein there is a longitudinallydisposed space between the left and right transmissions; furthercomprising a power take off shaft disposed in the space extendinganteriorly and driven by the motive power source for powering a poweredattachment adapted to be disposed at the anterior of the tractor.

In accordance with yet another embodiment, a tractor is providedcomprising base for supporting a motive power source, left and rightdriven wheels and a transmission for driving the left and right wheels;a handle structure coupled to the base for grasping by an operator frombehind the tractor; a drive system for driving the transmission withmotive power from the motive power source, further comprising a powertake off shaft extending anteriorly and driven by the motive powersource for powering a powered attachment disposed at the anterior of thetractor, further comprising a power take off adapter disposed at ananterior location on said tractor having a power coupling driven by saidpower take off shaft, said adapter allowing a single operator to connectand disconnect a powered attachment by manipulating handles of thehandle structure of the tractor from an operator's position.

In accordance with one embodiment of the current invention, a selfpropelled walk behind hand tractor has a power deck whereon is mountedthe motive source (motor) having a horizontal power output shaft, a pairof drive wheels fastened to left and right transmissions powered by themotor, a power take off (PTO) shaft in a horizontal plane approximatingthe centerline of the tractor, also driven by the motive source with aclutch for engagement and disengagement by the operator, an attachmentadapter plate affixed to the anterior of the hand tractor, and a handlebar assembly with respective control groups affixed to the posteriorportion of the power deck.

The power output shaft of the motive source is configured to drive thePTO and the motion power train through respective belt and pulleyarrangements disposed in a substantially vertical plane. A pulley drivesthe left and right transmissions with a belt loop and constant tensionidler arm and idler pulley configuration. Each transmission is suppliedwith an input shaft to which is fastened a driven pulley and an outputshaft coupled to the respective ground engaging wheel. Each transmissionis equipped with a speed control lever regulator which permitsadjustment of the ratio of the output ground engaging wheel to the inputshaft within a continuous range from reverse through neutral, where therespective ground engaging wheel is idle, to a maximum forward speed.

In one embodiment, there are primary and secondary left and rightcontrol levers mounted to the handles of the hand tractor as well as anomni-directional control lever preferably centered in the control panelof the hand tractor and preferably with a cruise control selector, forexample, of the friction type. The primary control levers are pivotallymounted and controlled by the operator's fore fingers like a bicyclebrake. In one embodiment, these levers are of the general design seen inthe prior art of Berrios U.S. Pat. No. 4,920,733. These primary controllevers are directly connected to the respective speed control leverregulators on the transmissions through linkages and pivot arms. Afterthe operator urges the omni-directional control lever forward with thecruise control feature deployed, the hand tractor can be slowed down,stopped or caused to go in reverse as the operator applies a squeezeforce to the respective primary lever. The operator can effect a turn inthis way by slowing down or reversing the direction of the respectivewheel. The secondary control levers are generally a pair of thumbactuated levers that pivot off the left and right handlebars adjacent tothe handle grips. These thumb levers are of the general design found inthe prior art of Wenzel U.S. Pat. No. 4,920,734. The secondary controllevers ride on a ball bearing affixed to the end of the control rodfitted to the primary levers. As the secondary control levers are urgeddownward by the operator's thumbs, the bearing rides along the flatsurface of the secondary control levers thereby urging the primarycontrol levers downward effectively speeding up the respective wheel.The operator can effect a turn in this way by speeding up the selectedwheel.

An omni-directional control lever is provided, preferably centered inthe control panel on the handle. The tractor may be provided only withthe omni-directional control, without the primary and secondarycontrols, if desired. The single control lever, effectively a joystick,is preferably operated through a spherical ball flange bearing. Thecenter of the spherical ball flange bearing is rigidly affixed under thecontrol panel. The housing of the spherical flange bearing is bolted toa control bracket. The control bracket is comprised of an inverted Ushaped channel bracket where the bottom of the U is bolted to thehousing of the spherical ball flange bearing and the sides of the U arefitted with forward facing flanges. These flanges are equipped withholes to connect to control linkages, e.g., control rods. The controllever handle is fastened to the bottom of the U shaped bracketconcentric to the spherical ball rigidly affixed under the control panelwith a shoulder bolt. The axis of the shoulder bolt is concentric to thecontrol lever handle and centered to a slot in the center of the controlpanel. The omni-directional control lever is fitted with ananti-rotational device and a pressure sensitive presence control switch.The anti-rotational device allows the control lever to move with arocking motion forward and aft, left or right while preventing therotation of the spherical ball bearing flange that could damage or lockthe control rods. The back of the U shaped control bracket preferablyhas a formed tab fitted to receive a shoulder bolt. The axis of theshoulder bolt is parallel to the bottom of the U shaped bracket andcentered to the housing of the ball bearing. The shoulder bolt is fittedto ride in a slot in a stop bracket affixed under the control panel. Thecontrol rod linkages are fitted to the holes in the forward facingflanges of the control bracket. These linkages connect to pivot armsthat rotate on split pivot rods affixed to the underside of the powerdeck. The split pivot rods allow for independent motion control of bothleft and right seamless transmissions/transaxles from reverse throughneutral to a maximum forward speed through actuation of the singlecontrol lever (and also through operation of the handle-mountedcontrols). A roller bearing is affixed to the far end of each speedcontrol lever regulator on the respective transmission. The rollerbearings ride in V shaped plates affixed to the end of the linkagesconnected to the respective pivot arms. The V shaped plates are providedwith spring tension to maintain constant contact between the V shapedplates and the corresponding roller bearings. A friction device ispreferably configured on the pivot rod which can be deployed by theoperator to allow for a determined course or disengaged to allow thesingle lever control of both transmissions with a return to neutral.This configuration allows the operator to steer the tractor as neededwith the left and right control levers beyond the course selected by thesingle lever control and when the hand controls are released the handtractor returns to the prescribed course. When the single lever handcontrol is deployed, the roller bearings stay centered in the V shapedplates as the transmission speed control lever regulators are urged intomovement by the action of the single lever hand control. The left andright hand controls are directly linked to the speed control leverregulators and when the operator manipulates either or both of the leftand right hand controls it directs the roller bearings to ride up ordown the V shaped plates, effectively enabling the operator to redirectthe tractor from the prescribed course to a new course. When the left orright hand controls are then released, the roller bearings are urgedback to the center of the V shaped plates by spring tension between theV shaped plate and the roller bearing, returning the hand tractor to theoriginally prescribed course.

A second pulley on the motor is belt connected to the driven pulleyfastened to the PTO drive line located below the drive pulley on themotor. The PTO is preferably engaged and disengaged with a mechanicalclutch brake with an electro-mechanical actuator, for example, anelectric motor driven vacuum pump actuator. An electromagnetic clutch ora movable idler pulley and a driven pulley brake configuration could bealternatively arranged without departing from the spirit of theinvention. An electrical interlock circuit is provided with presenceswitches on both handle grips and one presence switch on theomni-directional single hand control lever. This circuit only allows PTOengagement when the operator is present. The switches are furtherconfigured only to allow activation of the motor starter solenoid whenthe PTO switch is in the disengaged position and the parking brake isapplied, effectively preventing the operator from starting the enginewith the PTO engaged or transmission out of neutral.

The PTO driven pulley is sized to provide for proper speed reduction tothe PTO drive line. In a preferred embodiment, the pulley is sized toeffect a 3 to 1 speed reduction. This supplies a PTO speed toapproximate 1000 RPM. This enables the current invention to powerattachments such as a snow thrower or a power sweeper without furtherneed for speed reducing transmissions or additional pulleys and belts.It should be noted that this configuration enables the tractor to beeasily modified for differing PTO speed requirements as necessary bysimply changing the ratio of the pulleys and fitting the belt. The PTOdriveline is positioned in the centerline of the tractor in the narrowpassage created between the left and right transaxles and is supportedby bearings. The bearing closest to the driven pulley is mounted infront of the driven pulley, on a flange attached to the rear housings ofthe transaxles. This arrangement allows for easy belt removal andreplacement affording space behind the pulley to fit the belt. It alsodoubles as a reinforcement supporting and tying the two transaxlestogether. The posterior end of the PTO driveshaft protrudes beyond thepulley and has provisions for a connection means as the rear PTOattachment through an access hole in the power deck. This end mates witha corresponding mating driveshaft on the rear attachment. The drivenpulley is affixed to the driveline behind the roller bearings and infront of the lower portion of the power deck. The anterior end of thePTO driveline is supported by another bearing secured to a mountingflange affixed to the inside of the front attachment adapter housing.The front attachment adapter housing is configured to support the leftand right transaxles on top and bottom with standard hardware affixed atsuitable mounting points at the top and bottom of the left and righttransaxles. The front attachment adapter housing continues rearward andconnects to the lower leading edge of the power deck with two pivot pinsor bolts. This unique configuration allows for the front attachmentadapter housing to pivot away from the rear power deck when the topmounting bolts and the rear driveline are disconnected, enabling ease ofservice. The anterior end of the PTO driveline is splined and fitted toreceive a spring loaded self aligning coupler. The spring loaded selfaligning sliding coupler is accessed through an opening and resides atthe very edge of that opening in the front attachment adapter housing.In this way the coupler can recoil and self align when mated with themating driven coupler of the chosen front attachment.

The front PTO attachment adapter is comprised of a vertical plateaffixed with left and right guiding rails. The guiding rails are spacedon either side of the driveshaft. The guiding rails are positioned in atrapezoidal relationship. Whereas the top and bottom edges of theguiding rails are parallel, the left and right sides of the guidingrails form a trapezoid, narrowing to the top. This configuration allowsfor self alignment when coupling attachments. The top edges of theguiding rails are beveled rearwards thereby effecting a ramp forming atop mounted connecting hook. The top mounted connecting hook ispositioned to be in the line of sight of the operator enabling easygrappling of attachments by a single unaided operator. The bottomleading edges of the guiding rails are rounded enabling easy engagement.The mating receiver plate is connected to a corresponding attachment.The receiver plate is also trapezoidal and configured to mate directlyto the attachment adapter on the hand tractor. There are hitch pins onthe top and bottom of the receiver plate forming the two parallel sidesof the trapezoid on the receiver plate.

The hand tractor is equipped with a latching mechanism comprised of acable or rod actuated hook engaged with a lever mounted to the handle.In this way, the operator can remove and install attachments from theoperator's position. The latch protrudes through an opening in the frontPTO attachment adapter housing and is positioned directly below thespring loaded sliding power coupler access opening.

To couple an attachment, the operator lifts the handles of the handtractor slightly thereby guiding the top mounted connecting hook toengage the corresponding pin on the top of the receiver plate of theattachment. The operator then eases the handles downward causing thefront of the tractor to move upward as the weight of the tractornaturally urges the tractor to engage the latching mechanism with themating hitch pin on the bottom of the receiver plate of the attachment.With the latch engaged with the hitch pin on the bottom of the receiverplate the latching mechanism can then be deployed by the operator. Theoperator pulls the lever rearward causing the lever on the latchingmechanism to go over center. The hitch pin on the bottom of the receiverplate is guided along the rounded leading edges on the bottom of theguiding rails. In this way the two vertical plates on the tractor andthe attachment align and the spring loaded self aligning coupler engageswith the driven coupler on the attachment. The PTO on the tractor cannow be engaged by operating the clutch.

To disconnect an attachment, the operator releases the lever on thelatching mechanism and the handles are slightly lifted, causing thefront of the tractor to move downwardly. A secondary cable actuated by atrigger on the handle lifts the latch away from its mating point on theattachment and the hand tractor is moved further down at the front andaway by the operator, disengaging the top mounted connecting hook fromits mating pin on the attachment. The hand tractor is now separated fromthe attachment.

Other objects, features and advantages of the present invention will beapparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in greater detail in the followingdetailed description with reference to the drawings in which:

FIG. 1 is a left side perspective view of the tractor according to theinvention;

FIG. 2 is a front view of the tractor;

FIG. 2A is a side view of a detail of a portion of the PTO attachmentadapter showing the power coupler;

FIG. 2B is a side view of the PTO attachment adapter showing the toprearward bevel forming the connecting hook and the rounded bottom edgesof the guiding rails;

FIG. 3 shows the receiver plate disposed on an attachment to allow theattachment to be coupled to the PTO attachment adapter;

FIG. 4 is a rear view of the tractor showing the controls, control rodsand pivot rods;

FIG. 5 is a detail of the controls and linkages with the body of thetractor not shown;

FIG. 6 is a detail of a part of the split pivot rod structure for thecontrols for the tractor;

FIG. 7 is a top view of the hand controls on the handles;

FIG. 8 is a detail of the right hydrostatic transmission and part of itscontrol arrangement as well as the pulley system that drives the pumpsfor the hydrostatic transmissions and the PTO pulley system that drivesthe front PTO and also shows the rear PTO spline stub shaft and accesshole through the bottom of the power deck;

FIG. 9 shows a further detail of the right side hydrostatic transmissionand the control system for controlling they hydrostatic transmissionaccording to the invention;

FIG. 9A shows a perspective view of the control system of FIG. 9 at oneof the transmissions;

FIG. 10 shows schematically the right side control linkage operated bythe right side hand controls for controlling the right sidetransmission, there being a mirror image linkage for the left sidetransmission;

FIG. 11 shows a detail of the control linkage of FIGS. 10 and 12;

FIG. 12 shows schematically the control linkage for the single handjoystick control lever for controlling the right side transmissionaccording to the present invention, there being a mirror image linkagefor the left side transmission;

FIG. 13 shows a front view of the joystick single lever hand control;

FIG. 14 shows a top view of the joystick single lever hand control;

FIG. 15 shows a rear view of the joystick single lever hand control;

FIG. 16 shows a right side view of the single lever hand control;

FIG. 17 shows an attachment, in particular, a lawnmower attachment,coupled to the PTO attachment adaptor of the tractor;

FIG. 18 shows how the tractor is tilted to allow the receiving plate ofa powered attachment to be connected to the PTO attachment adapter;

FIG. 19 shows the control linkage for engaging/disengaging the PTOattachment adapter and for locking the attachment in place;

FIG. 19A shows the control linkage of FIG. 19 in its released state;

FIG. 20 shows the pulley and belt drive arrangement for driving the dualhydrostatic pumps and the rear bearing support bracket shown in a frontview;

FIG. 21 shows the pulley and belt drive arrangement for driving thefront PTO in a rear view;

FIG. 22 shows the drive shaft between the transmissions for the frontPTO and the rear PTO in a top view;

FIGS. 23A-C show details of the cruise control mechanism for the singlelever hand control, in particular, FIG. 23A shows a side view, FIG. 23Bshows how the cruise control attaches to the control linkage and FIG.23C shows a top view; and

FIG. 24 shows how the power deck and front adapter housing are hinged toprovide access to the belt drives.

DETAILED DESCRIPTION OF THE DRAWINGS

With reference now to the drawings, FIG. 1 is a left side view of thewalk-behind tractor with dual hydrostatic drive according to the presentinvention. FIG. 2 is a front view of the tractor 1 and FIG. 4 is a rearview. The tractor comprises a power deck 10 to which an internalcombustion engine 20, for example, a V twin engine as shown, is mounted.The internal combustion engine may be any suitable engine and of anysuitable design. Alternatively, another motive power source could beused. The invention applies to any type of motive power source. As isconventional, the internal combustion engine 20 includes a fuel tank 25,battery 15 for starting and ignition and suitable generator/alternator,exhaust system/muffler 160 and suitable known accessory systems toenable engine operation. In the tractor shown, the engine comprises ahorizontal shaft engine having its power shaft as indicate at 30 facingthe front of the tractor.

Mounted to the power deck 10 of the tractor is the front attachmentadapter housing 55 (FIG. 2, FIG. 8). Two hydrostatic transmissions 50(FIG. 2) are mounted side by side to the adapter housing 55. Left andright wheels 40 are driven by output shafts of the respectivetransmissions. The transmissions are conventional and of knownconstruction. As well known, each transmission has a driven pump todevelop hydraulic pressure, which is pumped to drive a hydraulic motor.The right side transmission 50 is shown in greater detail in FIGS. 8 and9. The adapter housing 55 is attached to the power deck 10, for example,by bolting. Preferably, the adapter housing 55 is bolted to the powerdeck 10 as shown at 56 at both sides at the top. These bolts can beremoved to obtain access to the drive belts for service. A hinge isprovided at the bottom of the adapter housing 55 where it connects tothe power deck 10. This allows the adapter housing 55 to hinge away fromthe power deck to allow for easy belt access/replacement.

As shown in FIG. 8, between the right transmission shown in phantom andthe left transmission (not shown) which forms a mirror image of theright transmission, a power takeoff (PTO) shaft 60 driven by a PTOpulley 70 is provided. The power take off shaft 60 is utilized toprovide power to powered attachments that can be connected to thetractor via an attachment adapter, which will be explained in greaterdetail below. In FIG. 8, the transmission right drive wheel axle isshown at 80.

Although the illustrated embodiment shows a tractor having an internalcombustion engine and dual hydrostatic transmissions, a different powersource could be employed, for example, an electric motor driven bybatteries. Further, the hydrostatic transmissions could be replaced bydual electric motors and an all-electric drive system could be employed,with the same effect as dual hydrostatic transmissions. Further, ahybrid internal combustion engine/electric motor drive system could beused, for example, an internal combustion engine (ICE) driving agenerator powering the electric motors with electrical control. Such ahybrid system could be designed with or without electrical storagebatteries, but would have the same functionality as the embodimentdescribed herein.

Turning again to FIG. 1, attached to the power deck 10 is a handlestructure 90 to which left and right handles 100 are attached. Left andright hand controls, to be described later, are provided on each handle100.

Also provided on the handle structure 90 is an engage and releaseoperating mechanism 120, shown in the released state, for the frontpower take off adapter which enables single operator connection anddisconnection of powered attachments. This will be described in greaterdetail in connection with FIG. 19.

A hydraulic reservoir 130 is provided for hydraulic fluid which is usedin the dual hydrostatic transmissions 50. As well known, a hydrostatictransmission comprises a pump driven by the motive power source thatpumps hydraulic fluid to a hydraulic motor which drives the drivencomponent, in this case, a drive wheel. The hydrostatic transmissionenables the corresponding wheel to be driven seamlessly between reverse,neutral and forward operating modes. Since each of the transmissions forleft and right can be controlled independently, the dual hydrostatictransmission drive employed in the present invention allows turns to bemade by driving one wheel faster than the other or with one wheel inneutral and furthermore, allows a zero radius turn by controlling onetransmission in reverse and the other forward.

According to the invention, as shown by the dashed inset circle in FIG.1, a control mechanism 140 for controlling each of the hydrostatictransmissions is provided. This control mechanism, which will bedescribed in greater detail in connection with FIGS. 9-12 relating tothe control linkages, allows the tractor to be controlled by the leftand right hand controls 201 and further according to the invention,alternatively, by a single control lever 600 of the joystick type thatcontrols a mechanism 150 (FIG. 4). This feature allows the tractoraccording to the present invention to be controlled with a single hand,thereby leaving the second hand free to control other functions, forexample, the chute direction control of a snow blower/snow throwerattachment. The transmission control mechanism is denoted generally byreference numeral 140 and shown by the encircled area in FIG. 1.

Although the invention contemplates that the single hand controlmechanism 150 is provided as an additional control mechanism to the handcontrols 201, it may be provided as the only control mechanism for thetractor, and the left and right hand controls 201 can be eliminated.

The single hand control mechanism is shown at 150 operated by lever 600(FIGS. 4 and 5) and will be described in greater detail later. Thesingle hand control mechanism is of the joystick type, allowing fore andaft control from a control neutral position to provide forward andreverse motion in which case each of the wheels are driven equally inthe forward and reverse direction to allow a straight ahead path, andfurther allowing for left and right control by moving the joystickcontrol in a transverse direction. According to the present invention,the joystick control is configured so that when the joystick is moved tothe left, the tractor will move to the right because the left wheel willbe speeded up. If the joystick control is moved to the right, thetractor will accordingly move to the left. This is intuitive becausemovement of the joystick control left and right will entailcorresponding movement of the back end of the tractor in that direction.

As will be explained below, the controls of the preferred embodiment ofthe present invention allow the operator to use either the dual handcontrols 201 or the single lever control 600. If the single levercontrol 600 is being used, it can be set to a prescribed course via acruise control feature, preferably of the friction type. The dual handcontrols can then be used to override the single lever control, in whichcase, when the dual hand controls are released, the tractor returns tothe prescribed course set by the single lever control. If the singlelever control is in neutral, return is, of course, to neutral.

The tractor preferably includes an electric power source, i.e., abattery 151, for powering an electric starter for the internalcombustion engine and for other accessory controls, e.g., anelectrically controlled PTO clutch.

Turning to FIG. 2, the front end of the tractor is shown. In particular,at the front end, disposed on the adapter housing 55 that houses thedual hydrostatic transmissions for the left and right wheels, is anattachment adapter plate 169. A power take off sliding coupler 170 isprovided extending through an opening in plate 169. The power take offcoupler 170 includes a coupling jaw 172 shown in greater detail in FIG.2A that is adapted to engage with a mating coupling jaw 174 that isprovided on the receiver plate 171 of the attachment that is to bepowered, as shown in FIG. 3. The coupling jaw 172 is slidably splined tothe PTO shaft 60 and spring biased outwardly by a spring 173. As shownin FIG. 2, the attachment adapter plate 169 is disposed on the front ofadapter housing 55 and includes two rails 180 that are inclined inwardlyso that they are more closely spaced together at the top than at thebottom, forming a trapezoidal arrangement. As shown in the side view ofFIG. 2B, the rails 180 each include a rearwardly sloped ramp 182provided at their top surfaces that are adapted to engage a pin 184provided on the receiver plate 171 of the attachment (FIG. 3). At thebottom of each of the rails 180, the rail is rounded as shown at 186 toallow the lower pin 188 of the attachment receiver plate 171 to beslidably received beneath it. A locking jaw 190 which is manipulated bythe operator locks the attachment in place by locking down on the pin188. The locking jaw, which moves both vertically and horizontally topull the attachment into position and to lock it down is manipulated bya control mechanism 120 provided on the handle structure 90. This willbe described in greater detail in connection with FIG. 19.

As previously described, the preferred embodiment of the tractoraccording to the present invention provides a dual control mechanism foroperating the tractor. The tractor includes left and right conventionalhand controls that allow two handed control of the tractor. Furthermore,the present invention provides a joystick single lever control thatallows complete control of the tractor movement via one hand. FIG. 4shows a rear view of the tractor showing the left and right handcontrols 201 as well as the single hand control mechanism 150 controlledby lever 600.

In particular, each of the left and right handles 100 include a primaryfinger control 200 that is pulled upwardly for reverse movement, thatis, for driving the respective wheel 40 in a reverse direction. Thecontrols further comprise a secondary thumb operated control 210 whichis pushed downwardly to achieve forward movement. In particular, thethumb control 210 is mounted on a pivot 212. A control rod attachmentpivot 215 is provided to which a control rod 220 is attached by a balljoint rod end 222. The pivot 215 is mounted to a shaft 224 that isaffixed to control lever 200 at fixation point 225. A bearing surface isprovided on the shaft 224. The bearing surface is disposed between thefixation point 225 on the primary control lever 200 and the control rodend that is fitted with the ball joint rod end 222 at pivot 215. Thebearing surface rides on a flat under-side portion of the secondarycontrol lever 210. As the secondary control lever 210 is urged againstthe bearing surface, the control rod 220 is moved downwardly, thuscausing the tractor drive wheel 40 to move in the forward direction.

Control rods 220A and 220B for the left and right transmissionsrespectively are each coupled to control levers 230A and 230B,respectively, mounted on a split shaft 240A, 240B, near the bottom ofthe tractor at the rear lower portion of the power deck 10. The splitshaft comprises left and right portions 240A and 240B which areindependent and separated at the center line of the tractor. Inparticular, the levers 230A and 230B freely rotate on theircorresponding split shafts 240A and 240B. Each lever 230A, 230B controlsa linkage that is directed anteriorly and which will be described ingreater detail in connection with FIG. 10, to control the correspondingleft or right transmission. Lever 230A is on the left side and lever230B is on the right side. As used herein, the letters A and B willdenote left and right, respectively, where corresponding mechanisms areprovided for left and right sides. For example, control rods 220 for theleft and right sides are designated 220A and 220B, respectively.

The single hand joystick mechanism 150, which will be described ingreater detail in connection with FIGS. 13-16, controls two control rods250A and 250B which likewise control the left and right transmissions.Control rods 250A and 250B are connected to respective levers 260A and260B also provided on corresponding ones of the split shafts 240A and240B. However, these levers 260 are pinned, keyed, or splined to therespective split shafts 240A and 240B so that the shaft rotates when thelever 260 is rotated. Also pinned, keyed or splined to the shaft 240 isa further lever 270, one for left (270A) and right (270B), which rotateswith the corresponding split shaft 240A or 240B. Thus, when the singlelever control mechanism 150 is manipulated to move the control rods 250Aand 250B, thereby causing rotation of the levers 260A and 260B, thecorresponding levers 270A and 270B rotate together with the shaft 240A,240B to control the corresponding left and right transmissions via alinkage to be described in greater detail in connection with FIG. 12.

A spring loaded presence control 280 is preferably provided on eachhandle 100 for operator safety. The control 280 operates a respectiveelectrical switch (not shown) to indicate operator presence whendepressed. A presence control switch is also provided on the singlelever hand control 150. The spring loaded presence controls 280 and onthe single lever control 150 will ground or otherwise disable theignition of the engine when the operator's hands are removed from all ofthe control levers (at least one control must remain in the operator'shand for the engine not to be shut off).

For safety, a parking lever (not shown) preferably must be set to startthe engine. At least one presence control must be depressed to keep theengine running when the parking brake is disengaged. The engine is alsopreferably arranged so that it will not start with the PTO engaged.Thus, the engine can be started only if the parking brake is on and thePTO is disengaged.

As described, single hand control 150 likewise contains apresence/deadman switch that requires the control to be presseddownwardly to ensure that an operator is present. Should the operatornot be present to hold down the control 150 (assuming neither of thecontrols 280 are depressed), the engine will be stopped. The control 150can be operated with a single hand, leaving the other hand free toperform other task related to the tractor, for example, manipulation ofa snow thrower chute or some other function.

FIG. 5 shows the control linkage unobstructed from the rear by the restof the tractor. FIG. 6 shows details of the control linkage for thesingle hand control 150 including details of the control lever 260A andthe control rod 250A. Each of the levers includes a spring 265 to urgethe lever arm to the neutral position.

FIG. 7 shows a top view of the two hand controls 201 and the handles100. In addition to the left and right hand controls 201 and the lever600 for the single hand control 150, additional functions include astarter switch 92, a power take off clutch engage switch 94 and a cruisecontrol selector lever 800.

FIG. 8 shows the right side transmission 50 mounted in the adapterhousing 55. The output shaft of the engine 20 is coupled to a power takeoff clutch 300 which may be of any convenient design including springactuated mechanical, electromagnetic, etc., as known to those of skillin the art. The present invention preferably utilizes a spring loadedmechanical clutch driven by a control linkage, not shown. In a preferredembodiment, a vacuum operated servo mechanism is utilized powered by anelectrically driven vacuum pump. The vacuum pump is energized to providea vacuum which operates a diaphragm to operate the clutch linkage toengage the clutch. Coupled to the output side of the clutch is a firstpulley 310 to which a belt 320 is affixed which drives a power takeoffpulley 70 which preferably has a diameter three times that of the pulley310 on the clutch to provide a 3-1 speed reduction. A spring loadedidler pulley 325 of conventional design is provided to ensure adequatetension on the belt 320. Further affixed to the clutch output is afurther drive pulley 330 which drives a belt 340 to operate the drivepulleys 350 for the hydraulic pumps of each of the left and righthydrostatic transmissions 50. Tension on belt 340 is provided by anidler/tension pulley 360 of conventional design. The details of theconnection of the pulleys 350 to the hydrostatic transmissions 50 arenot shown in FIG. 8.

According to the invention, a rear PTO can also be provided driven bypulley 70 through a shaft stub off pulley 70 and extending rearwardly.

The rear PTO is provided by a splined shaft stub 380 of shaft 60 onwhich driven pulley 70 is mounted. It is accessible through an opening71 provided in the rear of the front adapter housing 55 (see FIG. 4). Aconventional splined driven member 382 is adapted to lock with aconventional spring loaded lock 383 on the splined shaft stub 380 todrive a rear mounted attachment. Driven pulley 70 and shaft 60 aresupported by a bearing 375 mounted on a bearing support bracket 373(FIGS. 8 and 20) mounted between transmissions 50.

FIG. 20 shows in a rear view, the arrangement of the engine crankshaftpulley 330 and the left and right transmission hydraulic pump pulleys350 and idler pulley 360. The hydrostatic transmissions 50 are shownschematically. Idler pulley 360 is mounted to idler pulley bracket 370through a slotted hole 371 in the bracket. Idler pulley bracket 370 isfastened to the bearing support bracket 373 bolted between the left andright transmissions 50.

FIG. 22 is a top view of the shaft 60 which provides the front and rearPTOs. The shaft 60 is provided in the bearing 375 on a space between thetransmissions 50, shown only schematically. The shaft 60 is supported bya bracket 373 bolted between the transmissions.

FIG. 21 shows, in a front view, the pulley and belt arrangement for theengine crankshaft pulley 320 driven by the clutch 300, the PTO pulley 70and spring loaded idler 325. In both FIGS. 20 and 21, the directions ofmotion are shown by the arrows. FIG. 20 shows the pulley arrangementfrom the rear of the tractor and FIG. 21 shows the PTO pulleyarrangement viewed from the front.

Turning now to FIG. 9, the right side transmission 50 is shown. The leftside transmission is disposed on the left side and is a mirror image ofthe arrangement shown for the right side in FIG. 9.

Hydrostatic transmission 50 includes a speed control regulator lever 400which is operated to rotate a shaft 410 of the transmission to controlmotor speed and direction. When the lever is rotated in the directionindicated by arrow A, that is downwardly, drive axle 80 moves in thedirection shown by arrow C, that is, forwardly. The greater the rotationof the lever A, the greater the forward speed. Conversely, when thelever is moved in the direction shown by arrow B, the driven axle 80 isdriven in reverse. Lever 400 is directly pivotally coupled to a controlrod 420 via a pivot point 430. Rod 420 is operated by the hand control201 for the right side. FIG. 10 shows the right side transmissioncontrol but the left side is a mirror image of the right side control.

Turning to FIG. 10, when secondary thumb lever 210 is controlleddownwardly, that is, to move the corresponding wheel in the forwarddirection, control rod 220 is moved downwardly in the direction of thearrow shown in FIG. 10. This causes lever 230, which is mounted on thesplit shaft 240, to rotate clockwise as shown in FIG. 10. This causesintermediate control rod 430 to move in the forward directioncontrolling the lever 440 to rotate clockwise about a pivot shaft 450.Details of this construction are shown in FIG. 11. Pivot shaft 450 isdisposed at the front of power deck 10, near where power desk 10 joinsto adapter housing 55. A lever 460 is rigidly connected to the lever 440forming a bellcrank and pivots about the shaft 450 together with thelever 440 downwardly as shown in FIG. 10. This causes the control rod420 to move downwardly and thus rotate speed regulator level 400downwardly causing the right transmission to move axle 80 in the forwarddirection. The speed of wheel 40 depends on the amount of movement ofthe rod 420 and accordingly the amount that the thumb lever 210 isdepressed. Rod 420 is pivotally connected at the pivot 431 to the leverarm 400 and thus moves the lever arm 400 in the counterclockwisedirection. Pivot 431 includes a roller bearing arrangement which hasmounted thereto a flanged pulley 470 which rides on a V shaped track 475of a V shaped bracket 480 of the mechanism 140. The V shaped bracket 480is biased against the roller bearing pulley 470 by a spring 485. As willbe explained later, the V shaped bracket 480 is affixed to a control rod500 which is coupled via another linkage to the single lever controlmechanism 150 (FIG. 12).

This arrangement allows the flanged pulley 470 to ride on the V shapedtrack or cam surface 475. If the transmission is being controlled in theforward direction, that is, so that lever 400 moves counterclockwise ordownwardly, the pulley 470 accordingly moves downwardly on the track475A against the loading of the spring 485. Thus, as the pulley 470moves downwardly on the track 475A, the spring loaded bracket 480 movesaway from the control lever 400.

When the corresponding wheel 40 is being moved in the reverse direction,the pulley 470 will move upwardly on the track 475B against the bias ofthe spring 485. See FIG. 9. This will occur when the operator pulls upon the primary finger control 200, for operation in reverse speed.

As will be explained below, this arrangement allows the left and rightcontrols 201 to be used concurrently with (or alternatively to) thesingle lever control mechanism 150.

The vertical position of the V shaped bracket 480 is determined by theposition of the single lever hand control 150 as will be explainedbelow. That position corresponds to a neutral position when the V shapedbracket 480 is at a mid point of its upward and downward travel. In thiscase, when the single-lever hand control 150 is in the neutral position,the roller pulley 470 rides up and down the track 475A, 475B dependingupon operation of the hand controls 201. Should the single-lever handcontrol 150 be set to a prescribed course, for example, going forward athalf speed, the position of the V shaped bracket 480 will be verticallylower and if the hand controls 201 are not used, the pulley 470,disposed at the center of the V shaped bracket, will represent theprescribed course set by the hand control 150. When the single leverhand control 150 is returned to the neutral position, the transmissionspeed regulator lever 400 will likewise be returned to the neutralposition. FIG. 12 shows the linkage for the single lever control 150.FIGS. 13-16 will describe in detail the mechanical operation of thesingle lever control 150.

The linkage for the single lever control 150 is shown in FIG. 12. FIG.12 shows the right side linkage. A mirror image of the linkage shown inFIG. 12 will be provided on the left side for the left sidetransmission.

Turning to FIG. 12, the control rod 250B for the right side transmissionis coupled to the right side control flange of the single lever controlmechanism 150 which will be described in detail in connection with thedescription of FIGS. 13-16. Control rod 250B moves in the directionshown by the arrow in FIG. 12 when the corresponding driven wheel is tobe driven in the forward direction. The downward motion on rod 250Bcontrols lever 260 clockwise. Lever 260 is splined, keyed or pinned toshaft 240B and accordingly moves lever 270 also splined, keyed or pinedto the shaft, in the clockwise direction. This moves an intermediate rod510 in the forward direction as shown in FIG. 12. The rod 510 isconnected via a clevis to a bellcrank composed of levers 520 and 530which rotate on shaft 450. Lever 530 thereby moves rod 500 downwardly.Rod 500 is directly affixed to the V shaped bracket 480 and thus causesthe V shaped bracket to move downwardly. The V shaped bracket 480 isbiased against the transmission control lever 400 pulley 470 by spring485. As a result, downward motion of the bracket 480 moves the lever400, which stays centered by the pulley 470 at the center of the Vshaped bracket 480. At the same time, the control rod 420 movesdownwardly controlling the linkage shown in FIG. 10 so that it movescorrespondingly thereby controlling the positions of the levers 200 and210 of the hand controls.

The single lever control mechanism 150 preferably and optionallyoperates a friction mechanism to hold the lever 600 in a prescribedposition. Thus, the vertical position of the V shaped bracket 480determines the motion of the corresponding transmission in the forwardor reverse direction. That is, when the V shaped bracket is moveddownwardly, the transmission is engaged so that the wheel moves inforward rotation and when the V shaped bracket 480 is moved upwardly, bya corresponding reverse movement of the lever 600, the transmission isplaced in a reverse drive. The position of the V shaped bracket thusdetermines a prescribed course for the hand controls. When the V shapedbracket is centered, this is a neutral position, corresponding to theneutral position of the hand controls. However, when the V shapedbracket is displaced from the center position, a prescribed course(speed and direction) is determined. Because both transmissions arecontrolled, a prescribed course is thus set. Should the operator set aprescribed course via the single lever hand control mechanism 150, andthereafter use the hand controls 201, the further operation by the handcontrols will override the single lever control 150. In such case,pulley 470 rides up and down the track 475, depending on operation ofthe hand controls 201. However, upon discontinuing use of the handcontrols, the tractor will be returned to the prescribed coursedetermined by the setting of brackets 480 as determined by the settingof control 150.

As should be apparent from a review of FIGS. 10 and 12, when thecontrols are moved in reverse orientation to that shown, the directionsof the arrows reverses and the direction of the driven wheel motion isreversed.

A cruise control mechanism subassembly 1000 shown in FIGS. 23A-C isselected from a lever 800 on the control panel 90 that moves in aJ-shaped slot 801 (FIG. 7). When the lever 800 resides in the position802, the cruise control is selected. See FIG. 7. The cruise controlsubassembly 1000 of FIG. 23 consists of a fixed plate 1001 and a movableplate 1002. The fixed plate 1001 is affixed to the bottom of the powerdeck (see FIG. 12) and pivots on a shoulder belt 1003. Two holes 1004are provided in fixed plate 1001 to fasten the movable plate 1002 to thefixed plate 1000. The movable plate 1002 is fashioned with two slottedholes 1006. Two bolts 1008 mounted through holes 1004 and 1006 andprovided with compression springs 1010 and lock nuts 1012 providetension between the fixed and movable plates. A nylon type washer 1014is provided either between the plates or between the compression springand the movable plate to allow the plates to slide freely yet holdagainst the spring tension when the single hand control lever 600 isreleased. (As long as the operator depresses one of the presencecontrols 280, the engine will not stop.) The spring tension can beadjusted by adjusting the lock nuts 1012. Two of the cruise controlsubassemblies 1000 are provided, one for each left and righttransmission control. FIG. 12 shows one subassembly 1000 in its engagedposition engaging a pin 261 fitted to lever 260. FIG. 12 shows the righttransmission control from the single lever control 600. A similar cruisecontrol mechanism 1000 is provided for the left side transmission.

The slotted holes 1006 in the movable plate 1002 are configured toprovide only forward motion of the control lever 150. In this way,reverse is locked out when the cruise control is selected. This preventsthe operator from using reverse with the cruise control deployed toensure operator safety when the machine is used in the reversedirection.

The dual plate subassembly 1000 is spring biased by a torsion spring1015 on the pivot bolt 1003 to engage an extending pin 261 on the lever260. See FIGS. 23B and 12. A V-notch 1020 on the end of the movableplate 1002 engages the pin 261 when the cruise control is selected. Thedual plate subassembly 1000 pivots on a shoulder bolt 1003 that isfastened to the lower portion of the power deck 10. A cable 1022 (FIG.12) attaches between the subassembly 1000 and the cruise control selectlever 800 on the control panel 90 (FIG. 7) and is tensioned against thebias provided by spring 1015.

When the select lever 800 is operated to select the cruise control(lever 600 in neutral), spring 1015 causes the subassembly 1000 to movedownwardly, so that the notch 1020 engages the pin 261 to engage thecruise control. When the cruise control is not selected by the control800, the cable 1022 moves the subassembly 1000 away from the pin 261against the bias provided by spring 1015. In this way, the tractor willnot follow a prescribed course and the single hand lever control 600will return to the neutral position when released.

FIGS. 13-16 show details of the single lever control 150. The controlcomprises a control lever 600 mounted, for example, by bolting, to abracket 610. Bracket 610 is slidable vertically on an upstanding bracket620 that is affixed to an inverted U shaped control bracket 630. Bracket610 is movable vertically in slotted holes 640 on pins 650 (FIG. 16)that are affixed to the bracket 610. A spring loaded presence switch 660is provided having a plunger 670. In the position shown with the switchplunger 670 undepressed, the transmissions are in neutral. The enginecan be started when the switch is in this position. When the control 600is engaged by a user by pressing it downwardly, the plunger 670 isdepressed, providing an indication that an operator is present. Shouldthe operator release the control, preferably the engine will be stopped.The spring in the switch 660 is used to return the control lever 600 tothe undepressed position. Alternatively, another or additional springcan be provided to accomplish this function.

Upstanding bracket 620 is mounted to the U shaped control bracket 630 towhich is mounted on its underside a spherical ball flange bearing 680.The flange of the bearing is mounted to the U shaped bracket by suitablebolts 690. A spherical ball 700 is free to rotate in the flange 680.Attached to the ball 700 is a shaft 710 which is affixed to a furtherbracket 720. Bracket 720 is in turn affixed to the center panel of thehandle structure 90 of the tractor. Shaft 710 is affixed to bracket 720by a suitable shoulder nut connection 730 so that it is fixed to thebracket 720. In this way, the U shaped bracket 630 can rock fore and aftand left and right thereby controlling the control rods 250A and 250B.FIG. 13 shows the control mechanism 150 from the front of the tractor.

Accordingly, when the control lever 600 is moved in the forwarddirection, the rods 250A and 250B are pushed downwardly with theoperation as described in connection with FIG. 12. When the controllever 600 is moved rearwardly, the rods 250A and 250B are pulledupwardly thereby controlling the transmissions to cause a reversemovement.

When the control lever 600 is moved to the right, corresponding to themovement in the direction “L” in FIG. 13, control rod 250B is moveddownwardly and control rod 250A is moved upwardly thereby causing theright transmission to go into forward direction and the lefttransmission to go into revise direction, thereby causing a left turn.When control lever 600 is moved to the left, corresponding to “R” inFIG. 13, rod 250A moves downwardly and rod 250B moves upwardly therebyplacing the right transmission in the reverse direction and the lefttransmission in the forward direction causing a right turn.

FIG. 14 shows the single lever control mechanism 150 from a top viewwith the rear of the tractor at the bottom of the figure. The controllevers 250A and 250B are mounted on forwardly extending extensions 632of U shaped bracket 630. Bracket 630 is able to move fore and aft andleft and right and is prevented from moving rotationally by a pin 740that is bolted to the bracket 630 via a tab 750 on bracket 630. Anupturned projection 760 of the bracket 720 has an elongated slot 770therein (see FIG. 15), which allows the pin 740 to move verticallythereby allowing the forward and aft and left and right rocking motionsbut preventing rotational movement of the U shaped bracket 630.

FIG. 16 shows a right side view of the control mechanism 150. Switch 660is mounted to the bracket 610 via screws 770. Clearance for and accessto the screw heads 770 is provided by a slot 780 in the bracket 620.

FIG. 17 shows the tractor 1 coupled to an exemplary powered attachment 2comprising a lawn mowing attachment. FIG. 18 shows how the operatormanipulates the tractor to engage the powered attachment. The operatormoves the handles upwardly, as shown, causing the front of the tractorto move downwardly. The operator causes the top hooks 182 of the rails180 (FIG. 2B) to engage under the top pin 184 of the receiver plate 171of the attachment. This is visible from the operator's position. Oncethe hooks 182 engage the pin 184, the operator moves handles 100downwardly. The weight of the tractor 1 causes the rails 180 on theadapter plate 169 to engage the rails 183 on the receiver plate 169 ofthe attachment and force the rails 180 and 183 into alignment. Thisaligns the coupling 172 on the adapter plate 169 with the matingcoupling 174 on the attachment receiver plate, which are then coupledfor transmitting power to the attachment.

The operator then operates the mechanism 120 (FIG. 19) to lock the hook190 against the lower pin 188 of the receiver plate. In particular,mechanism 120 includes a pivotable handle 900 that rotates forwardly indirection 901 on pivot 902. FIG. 19A shows the mechanism pivoted intothe released state. This movement operates cable 910 that moves hook 190forward via lever 912. This allows the hook 190 to clear the pin 188prior to locking it on the pin 188. A trigger lever 903 coupled to acable 920 allows the hook 190 to be raised above the pin 188 when it issqueezed.

When the operator desires to lock the receiver plate 171 to the adapterplate 169, the operator releases the trigger lever 903 to drop the hook190 down in front of the pin 188. Then, lever 900 is raised in thedirection opposite arrow 901 (i.e., counterclockwise) to draw the hookrearwardly to lock the receiver plate 171 to attachment adapter plate169 and cause coupling 172 and 174 to couple. The PTO clutch can then beengaged to power the attachment.

To release the attachment, the reverse procedure is employed. The lever900 is pivoted forwardly in the direction of arrow 901. This moves thehook 190 forward away from pin 188. Then, while squeezing lever 903 toraise the hook 190, the handles 100 of the tractor are raised, tippingthe front of the tractor downward. This will release the pin 188 fromcontact with adapter plate 169, separating the bottom of the attachmentfrom the tractor and separating the power couplings 172 and 174. Then,the handles are tilted down a little more to separate upper pin 184 fromthe top hooks 182 of rails 180. The tractor is moved rearwardly tocomplete the separation of the attachment.

FIG. 24 shows how access can be obtained to the belt drives tofacilitate changing and servicing the belts and drive mechanisms.

First, with reference to FIG. 1, bolts 56 are undone. This decouples thetop of the front adapter housing 55 from the top of the power deck 10.The power deck 10 and adapter housing 55 pivot as shown in FIG. 24 athinge point 11. The belts 320 and 340 will flex between the pulleys onthe engine and those mounted to the adapter housing 55, but can noweasily be removed and changed.

The present invention describes a walk-behind tractor with front andrear power take-offs, a front mounted power attachment mechanism and asingle hand drive control. These concepts can also be employed withother types of tractors including stand-up riding tractors, sit downtractors etc. Furthermore, the powered attachments need not be onlymoving attachments, such as snow blowers, brushes and lawn mowers, forexample. The attachments could also be of the stationary type, such aspressure washers, air compressors, etc. In such case, it will benecessary to provide an interlock override such as a switch operated bythe stationary attachment to override the presence controls provided onthe hand controls (as there is no need to have an operator present atthe controls if a stationary powered attachment is being used). In sucha case, since the operator will not be standing behind the handcontrols, the interlocks on these controls must be defeated in order toallow the stationary powered attachment to be used.

Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art. It ispreferred, therefore, that the present invention be limited not by thespecific disclosure herein, but only by the appended claims.

What is claimed is:
 1. A tractor comprising: a base for supporting amotive power source, left and right driven wheels, and left and righttransmissions for the respective left and right wheels; a handlestructure coupled to the base for grasping by an operator from behindthe tractor; a drive system for driving each of the left and righttransmissions with motive power from the motive power source; whereinthe left and right transmissions are hydrostatic transmissions, furthercomprising a speed regulator control lever on each transmission thatallows seamless control of the transmission from reverse speed throughneutral into forward speed; and a transmission control structuralmechanism coupled to each speed regulator control lever; further whereinthere is a longitudinally disposed space between the left and righttransmissions, further comprising a power take off shaft disposed in thespace extending anteriorly from the space and driven by the motive powersource for powering a powered attachment arranged to be attached at theanterior of the tractor, and further comprising a shaft extension ofsaid power take off shaft extending posteriorly from the space fordriving a rear power take off for powering a rear mounted poweredattachment.
 2. The tractor of claim 1, further comprising a power takeoff clutch coupled to an output shaft of said motive power source, saidclutch being selectively engageable by the operator to power said powertake off shaft.
 3. The tractor of claim 2, further comprising a beltdrive coupling said clutch to a driven pulley provided on said powertake off shaft.
 4. The tractor of claim 3, further wherein said basecomprises a power deck for the motive power source and an adapterhousing for mounting said transmissions, said adapter housing beingreleasably coupled to said power deck to provide access to said beltdrive.
 5. The tractor of claim 4, further comprising a hinge couplingsaid adapter housing and power deck allowing the adapter housing to bepivoted away from the power deck to expose the belt drive.
 6. Thetractor of claim 3, further comprising a second belt drive for couplingthe motive power source through said clutch to drive pulleys forhydraulic pumps of each of said transmissions.
 7. The tractor of claim2, further comprising a spring loaded switch connected into anelectrical circuit requiring operator presence in order to engage thepower take off clutch.
 8. The tractor of claim 7, wherein said switch isconnected into a circuit that prevents the motive power source frombeing started if the power take off clutch is engaged.
 9. The tractor ofclaim 1, wherein the tractor is a walk-behind tractor.
 10. The tractorof claim 2, further comprising a first pulley at an output of saidclutch and a PTO pulley on said power take off shaft driven by a powertake off drive belt between said pulleys.
 11. The tractor of claim 10,further comprising a second pulley on the output of said clutch drivinga transmission drive belt, said transmission drive belt driving pulleysengaging hydraulic pumps of said left and right transmissions.
 12. Thetractor of claim 1, wherein the handle structure comprises left andright handles, the left handle comprising a left transmission controland the right handle comprising a right transmission control; wherebythe operator can independently control the left and right transmissionsusing the left and right transmission controls using both left and righthands.
 13. The tractor of claim 1, further comprising a power take offadapter disposed at an anterior location on said tractor having a powercoupling driven by said power take off shaft, said adapter allowing theoperator to connect and disconnect the powered attachment bymanipulating handles of the handle structure of the tractor from anoperator's position.
 14. The tractor of claim 1, wherein the power takeoff shaft is arranged in said longitudinally disposed space to drive theanteriorly disposed power take off and is coupled to said shaftextension driving said rear power take off.